Everyone knows AMC's zombie drama "The Walking Dead" is a hit. What's less talked-about is how the show has evidently discovered some kind of anti-aging miracle potion that allows it to defy typical TV ratings trends.

"Walking Dead" wrapped up the first part of its Season 4 on Sunday, with a mid-season finale that drew 12.1 million total viewers, according to Nielsen.

It's the highest-rated series in the history of cable TV. And even if it aired on broadcast TV, "Walking Dead" would be TV's top show in the key adults ages 18 to 49 demographic, with a 6.6 rating. Only NBC's Sunday night NFL games yield a higher number.

What's unusual is that "Walking Dead's" audience really isn't getting any older -- despite the fact that the show is in its fourth season, and that it's harder than ever to get young people to watch scheduled TV.

Typically, shows that become hits attract their youngest viewers during the first few seasons. Then, as that audience ages a bit and viewers a few years younger seek out newer fare, the average age begins an inevitable climb toward the upper reaches of the demo.

That's not happening with "Walking Dead." The AMC show has a median viewer age of 33.2 so far this season, according to numbers provided by New York ad firm Horizon Media on Wednesday. That is slightly younger than the average age during its premiere season in 2010 (33.8).

What's that mean? Well, given that "Walking Dead's" overall audience is more than twice as large now as it was then, millions of those new viewers must be coming from the pool of people over 18 but younger than 33. In other words, mainly twentysomethings. By TV standards, that's very young indeed -- and exactly the hard-to-get audience everyone wants. Remember, we are in a world where ABC, CBS and NBC are struggling just to keep people in their 40s from fleeing.

Naturally, all this is music to the ears of advertisers, not to mention AMC executives.

But it's a safe bet broadcast executives wouldn't mind if you forgot these stats.

The final episode of "The Walking Dead" of 2013 saw a lot of characters' blood shed, including kindly old Hershel, the heart and soul of the group, and Meghan, a sweet little girl introduced just two episodes ago. While many fans expressed outrage and sadness over the passing of those other...

A story about people who love one another made by people who clearly love one another, "Parks and Recreation" ended its seven-season, zigzag run through prime time Tuesday night on NBC. In the final shot, star Amy Poehler, as public servant Leslie Knope, faced the camera, all aglow, and...

The finale of "Parks and Recreation" aired on NBC on Tuesday night, and in a bold move, the show went further into the future than it already had in its final season, revealing what the public servants of Pawnee, Ind., would be doing decades from now.

Grammy Award-winner Patti LaBelle and Michael Sam, the NFL's first openly gay draft pick, are two of the 11 celebrities announced Tuesday as part of the upcoming 20th season of ABC's "Dancing With the Stars."